The invention relates to methods for treating cystic fibrosis.
Cystic fibrosis is a hereditary disease that affects a number of organs, particularly the lungs and pancreas. The exocrine glands of a cystic fibrosis patient secrete abnormally thick mucous, which blocks the patient""s bronchi. As a result, many cystic fibrosis patients have chronic bronchitis; they are also susceptible to pneumonia and other pulmonary infections. In particular, cystic fibrosis patients are susceptible to Pseudomonas infections.
As there is currently no cure for cystic fibrosis, treatments for this disabling disease focus on alleviating the symptoms of the disease. Unfortunately, the infections of many cystic fibrosis patients do not respond to the antibiotics traditionally used to treat pulmonary infections.
In one aspect, the invention features a method for treating cystic fibrosis in a mammal, such as a human; the method includes administering to the mammal an effective amount of a histatin or a histatin fragment. In preferred methods, the histatin fragment has between 8 and 20 amino acids, inclusive, and more preferably has between 8 and 12 amino acids, inclusive.
For example, the histatin fragment may have the amino acid sequence Ala-Lys-Arg-His-His-Gly-Tyr-Lys-Arg-Lys-Phe-His(SEQ ID NO: 1). Preferably, at least one of the amino acids in this sequence is a D-amino acid. In one preferred method, the fragment has the amino acid sequence D-Ala-D-Lys-D-Arg-D-His-D-His-D-Gly-D-Tyr-D-Lys-D-Arg-D-Lys-D-Phe-D-His.
In another preferred method, the histatin is histatin 5 (SEQ ID NO: 2) (shown in FIG. 2); preferably, at least one amino acid of the histatin 5 is a D-amino acid. In yet another preferred method, the histatin or histatin fragment has at least one modification selected from the group consisting of an acyl addition at the N-terminus; a carbamyl addition at the N-terminus; and an amide addition at the C-terminus.
In a second aspect, the invention features a method for treating cystic fibrosis in a mammal, such as a human; the method includes administering to the mammal an effective amount of a histatin-related peptide having between 8 and 20 amino acids, inclusive, where the peptide has the amino acid sequence: R1-R2-R3-R4-R5-R6-R7-R8-R9-R10-R11-R12-R13-R14-R15-R16-R17-R18-R19-R20-R21-R22-R23(SEQ ID NO: 3), where R1 is Asp or is absent; R2 is Ser or is absent; R3 is His or is absent; R4 is Ala, His, Leu, or is absent; R5 is Lys, Gln, Arg, Orn, or another basic amino acid; R6 is Arg, Gln, Lys, or another basic amino acid; R7 is His, Phe, Tyr, Leu, or another hydrophobic amino acid; R8 is His, Phe, Tyr, Leu, or another hydrophobic amino acid; R9 is Gly, Lys, Arg, Ser, or a basic amino acid; R10 is Tyr; R11 is Lys, His, Phe, Leu, or another hydrophobic amino acid; R12 is Arg, Gln, Lys, or another basic amino acid; R13 is Lys, Gln, Arg, Orn, another basic amino acid, or is absent; R14 is Phe or is absent; R15 is His, Phe, Tyr, Leu, another hydrophobic amino acid, or is absent; R16 is Glu or is absent; R17 is Lys or is absent; R18 is His or is absent; R19 is His or is absent; R20 is Ser or is absent; R21 is His or is absent; R22 is Arg or is absent; and R23 is Gly or is absent.
In preferred methods, at least one of R7, R8, R11, or R15 is Phe. For example, R7 is Phe; R8 is Phe; R11 is Phe; and/or R 15 is Phe. In one preferred method, all of R7, R8, and R15 are Phe. In other preferred methods, R9 is Lys and/or R11 is His. In other preferred methods, at least one of R7, R8, or R15 is Tyr. Preferably, all of R7, R8, and R15 are Tyr.
In another preferred method, at least one of R5 and R13 is Gln; preferably, both R5 and R15 are Gln. In a different preferred method, at least one of R5 and R13 is Orn; preferably, both R5 and R13 are Orn.
In some preferred methods, all of R1, R2, and R3 are absent. In other preferred methods, both R22 and R23 are absent, all of R20, R21, R22, and R23 are absent, or all of R18, R19, R20, R21, R22, and R23 are absent. Examples of preferred peptides include peptides which have the amino acid sequences: Ala- Lys-Arg-Phe-Phe-Gly-Tyr-Lys-Arg-Lys-Phe-Phe (SEQ ID NO: 4) (P-113-F4.5.12); Ala-Lys-Arg- His-His-Lys-Tyr-Lys-Arg-Lys-Phe-His (SEQ ID NO: 5) (P-113-K6); Ala-Lys-Arg-His-His-Gly- Tyr-His-Arg-Lys-Phe-His (SEQ ID NO: 6) (P-113-H8); Ala-Lys-Arg-His-His-Lys-Tyr-His-Arg- Lys-Phe-His (SEQ ID NO: 7) (P-113-K6H8); Ala-Lys-Arg-Tyr-Tyr-Gly-Tyr-Lys-Arg-Lys-Phe- Tyr-NH2 (SEQ ID NO: 8) (P-113-Y4.5.12); Ala-Gln-Arg-His-His-Gly-Tyr-Lys-Arg-Gln-Phe-His- NH2 (SEQ ID NO: 9) (P-113-Q2.10); or Ala- Orn-Arg-Tyr-Tyr-Gly-Tyr-Lys-Arg-Orn-Phe-Tyr-NH2 (SEQ ID NO: 10) (P-113-K2.10O-H4.5.12Y ).
Preferably, the peptide has at least one modification selected from the group consisting of an acyl addition at the N-terminus; a carbamyl addition at the N-terminus; and an amide addition at the C-terminus.
By xe2x80x9chydrophobic amino acidxe2x80x9d is meant an amino acid selected from the group consisting of Ala, Val, Leu, Ile, Phe, Trp, Met, and Thr.
By xe2x80x9cbasic amino acidxe2x80x9d is meant an amino acid selected from the group consisting of Lys, Arg, Orn, Gln, and Asn.
The invention provides effective methods for treating cystic fibrosis. According to the invention, histatins, histatin fragments, and histatin-related peptides can be used to combat Pseudomonas infections and other pulmonary infections in cystic fibrosis patients. Histatin derivatives are effective in treating these infections, even in cases where the infections are resistant to traditional antibiotics.
Other features and advantages of the invention will be apparent from the following description and from the claims.